2. Introduction
The paired parotid, submandibular, and sublingual
glands are referred to as the major salivary glands;
Each is anatomically, histologically, and functionally
unique.
The minor salivary glands are submucosal clusters of
salivary tissue present in the oral cavity, paranasal
sinuses, pharynx, and upper respiratory tract.
It has been estimated that more than 750 minor
salivary gland clusters are present.
3. Embryogenesis
• All salivary glands -common embryogenesis- local
proliferations of surface epithelium into the
underlying mesenchyme- similar anatomic
structure.
• Secretory/parenchymal tissues arise from these
proliferations - of ectodermal origin for the major
salivary glands and of either ectodermal or
endodermal origin (depending upon the
anatomic location) for the minor salivary glands.
• Stroma -mesodermal origin and an additional
component of neural crest.
4.
5. • Parotid anlagen -first to develop (4-6th wk)
• Submandibular gland anlagen- 6th wk
• Sublingual gland anlagen- 7-8th wk
• Minor salivary glands –do not start to develop
until late in the 12th wk of intrauterine life.
6. • Epithelial buds enlarge, elongate, and branch, the
last process being induced by the mesenchyme
surrounding the epithelium.
• Then canalization process results from a
differential in the mitotic rate- completed prior
to the development of lumina in the terminal
buds -develop into the acini.
• epithelial cells lining the ducts, tubules, and acini
then differentiate.
7. • Surrounding the acini are- myoepithelial cells that
reach their peak density by the 24th wk in the
submandibular glands 25th wk in the parotid glands
• Interaction of the salivary gland parenchymal
and stromal elements with the ANS is necessary
for salivary development and function,
– as sympathetic nerve stimulation leads to acinar
differentiation,
– parasympathetic is important for overall glandular
growth.
8. • In the parotid glands,
– ducts are canalized by the 10th wk
– terminal buds by 16th wk
– secretions commence in 18th wk
• In the submandibular glands,
– acini start to differentiate by -12th fetal week.
– Serous secretory activity starts at 16th fetal week,
– increases until the 28th wk, and then diminishes.
• These serous secretions contribute to the amniotic fluids, and
contain amylase and possibly nerve and epidermal growth
factors.
• The mucous acini develop postnatally. The mucosal minor
salivary glands are not morphologically mature until the
twenty-fifth fetal week.
9. • Although the parotid anlagen are the first to
emerge, they become ‘‘encapsulated’’ only after
the submandibular and sublingual glands have
become encapsulated.
• Thus, at the completion of embryogenesis, the
parotid glands have lymph nodes and lymphatic
channels within the gland’s capsule, while the
submandibular and sublingual glands do not.
10. • In addition, salivary epithelial cells can be included
within the intraparotid and periparotid lymph nodes
(MALT) during their process of encapsulation.
• These LNs supply all the major salivary glands with IgA
producing plasma cells that are important components
of mucosa-based immunity.
• This special embryogenesis of the parotids and their
LNs play a role in the development of Warthin’s tumors
11. Parotid Gland
• Largest
• Palpable superficial portion .
• Fascia –SLDCF,
– densest over lateral and inferior aspects,
– filmy or incomplete over medial surface
• Fascial extensions- subdivide the gland into
lobules.
12. Space of the Parotid Gland
• SLDCF splits to enclose the parotid gland.
• the parotid gland cannot be shelled out, leaving
behind a real compartment with strong fascial
boundaries.
• However, conceptually, this space encloses the
parotid gland, the parotid lymph nodes, and
portions of the external carotid artery and the
posterior facial or retromandibular vein
13.
14. • Weight: 14-28 g (adult male)
• Measures: 5.8 cm craniocaudally and 3.4 cm
ventrodorsally.
• Female-slightly smaller.
• ∼80% is superficial to the masseter, ramus, angle.
• rarely extends cranially to the zygoma.
15. • Superficial parotid lies below and anterior to the
external auditory canal and mastoid tip,
• extending caudally to angle of mandible.
• deep aspect (∼20%) extends medially through
stylomandibular tunnel
• Present b/w posterior edge of ramus and anterior
borders of the sternocleidomastoid muscle and the
posterior belly of the digastric muscle.
• Stylomandibular ligament separates it from the
submandibular gland.
16.
17. • Despite the commonly used terminology,
there is actually no anatomic division into
separate superficial and deep parotid lobes, a
nomenclature based on the facial nerve as a
reference plane within the gland.
• However, anatomically correct terminology in
which the mandible has become the reference
point is gaining popularity.
18. • Main trunk of the facial nerve exits the skull
base via stylomastoid foramen, immediately
producing three small branches: the posterior
auricular, posterior digastric, and stylohyoid
nerves.
• Courses laterally around the styloid process,
superficial to the posterior belly of digastric.
19.
20. • Distal to this, it pierces the posterior capsule of
the parotid gland.
• Continues within the gland lateral to the
posterior facial vein (retromandibular vein) and
the more medially situated external carotid
artery.
• It then divides via variable anatomic patterns into
the temporal, zygomatic, buccal, mandibular, and
cervical branches.
21. • parotid ductal organization has an arborizing
or tree-like branching pattern.
• As one traces proximally from the main
parotid duct (Stensen’s duct) toward the
terminal acini, the ducts become progressively
smaller, with more numerous branches
22.
23. • Histologically, the main excretory ducts can be seen to
lead into the
– striated ducts (columnar)
– the intercalated ducts (cuboidal epithelium surrounded by
myoepithelial cells),
– and the terminal acini.
• In the adult, the parotid acini are purely serous; it is
only in the neonatal period that some mucous cells are
found.
• Sebaceous elements may be uncommonly found in the
parotid gland and are thought to explain the sebaceous
differentiation that may be seen in some salivary
tumors.
24. • Parotid parenchyma has abundant adipose tissue,
adipose to glandular tissue of 1;1.
• The parotid intercalated ducts are long and thin
compared to the submandibular gland.
• The sublingual gland has the shortest and widest
intercalated ducts.
• These variations in intercalated duct morphology
may be related to the types of secretions in each
of these glands.
25. • Stensen’s duct- 7 cm long;
• Course: anterior parotid-over the masseter and buccal
fat pad- abruptly courses medially- pierce the
buccinator muscle (90° angle)- obliquely and inferiorly
for a short distance between the buccinator and oral
mucosa- buccal mucosa, opposite the second upper
molar.
• An accessory parotid duct may join Stensen’s duct as
the latter passes over the masseter muscle.
• Accessory parotid tissue is present in about 20% of the
population, usually about 6 mm anterior to the main
parotid gland, adjacent to Stensen’s duct.
26. • Lies cranial to stensen’s duct, with only one excretory duct
entering stensen’s duct.
• There may be multiple accessory glands, each with its own
primary drainage into Stensen’s duct.
• The parotid gland contains 3 to 32 (average, 20)
intraglandular lymph nodes interconnected by a plexus of
lymphatics that drain the ipsilateral upper and midfacial
skin.
• The palatine tonsil also drains into the parotid lymph
nodes.
• parotid lymph nodes drain primarily into internal jugular
chain (level IIA) and also into the upper spinal accessory
chain (level IIB).
27. • The parotid is innervated from the sympathetic
plexus on the carotid artery,
• parasympathetic innervation- glossopharyngeal
nerve via auriculotemporal n.
• parasympathetic fibers may also be contributed
via the facial nerve through the otic ganglion.
• sympathetic nerves- vasoconstriction,
• Parasympathetic - secretion.
28. Proper surgical planning requires that the surgeon be
informed as to whether a parotid mass is limited to the
superficial gland or extends to the deep portion of the gland.
If a parotid mass extends into the parapharyngeal space, its
size is important, as such a mass will require one of several
modifications of the standard surgical parotidectomy for
successful extirpation without violation of the tumor capsule.
The surgical modifications vary, depending on tumor size,
from simple anterior dislocation of the temporomandibular
joint (TMJ), to an angle mandibulotomy, to a midline
mandibular split with dislocation of the TMJ.
If the deep neck mass can be shown not to be of parotid
gland origin, a lateral neck or submandibular approach is
used.
29. Blood supply
• facial and external carotid arteries,
• richer vascular supply to the ductal than the
acinar system.
• blood flow is parallel, but in opposite direction
to the salivary flow.
30.
31.
32.
33.
34.
35. Submandibular Gland
• Second largest salivary gland,
• Weight: 10- 15 g (1/2 parotid).
• occupies most of the submandibular triangle;
• folded around the free edge of the mylohyoid
– referred to as being divided into superficial and deep
lobes.
36.
37. Submandibular Gland
• Superficial portion bounded
– anteriorly and inferiorly by the anterior belly of the
digastric muscle,
– posteriorly by posterior belly of the digastric and
stylohyoid muscles,
– laterally by lower border of the mandible and the medial
pterygoid muscle .
• Posteriorly, it is separated from the parotid gland by
– stylomandibular ligament.
• The floor or deep surface of the submandibular
triangle
– formed by the mylohyoid and hyoglossus muscles.
38. Space of the Submandibular Gland
• This space can’t be considered a real space in
the sense that the submaxillary gland can be
easily shelled out of it, leaving the SLDCF
behind as a capsule.
• Instead, the septa of the gland are continuous
with the capsule.
39. Submandibular Space
• Overall, this space is the volume described within the mandibular
arch, limited above by the mucosa in the floor of the mouth and
caudally by the SLDCF as it extends from the hyoid bone to the
mandible.
• Divided into an upper and a lower portion by the mylohyoid muscle
• Submandibular gland lies partially above and partially below its dorsal
edge.
• In fact, the upper and lower portions of the submandibular space
communicate freely with each other around dorsal margin of the
mylohyoid muscle.
• Also free communication between the left and right sides of this
space.
40. • Cranial portion of the submandibular space is often called the
sublingual space.
– filled with loose connective tissue that surrounds both sublingual glands
and their ducts, the lingual and hypoglossal nerves, the lingual arteries,
and the smaller or deep portion of each submandibular gland along with
its hilum and Wharton’s duct.
• On either side, the lower or caudal portion of the submandibular
space is usually referred to as the submaxillary space, and the larger
superficial portion of the submandibular gland and its lymph nodes
lie within its loose connective tissue.
• The facial artery and vein as well as the digastric muscle are also in
each submandibular space.
• The submental triangle and the submandibular triangles of the neck
are the superficial landmarks that correspond to the region of this
space
41. • Superficial portion- SLDCF, platysma, anterior facial
v., marginal mandibular n. runs adjacent to the
gland.
• The anterior facial vein- useful imaging landmark to
help determine if a mass arises within or adjacent to
the submandibular gland.
– A lesion arising within the gland will never be separated
from the gland by this vein.
– If the vein separates the mass and the gland, the lesion
may have originated from submandibular lymph nodes
(level IB) or the adjacent soft tissues.
42.
43.
44. • lingual nerve and submandibular ganglion are
superficial (lateral) to the gland,
• hypoglossal nerve with its accompanying vein
lies deep to it.
• Wharton’s duct- 5 cm long, with thinner walls
than Stensen’s duct.
Submandibular Gland
45. • Along this course, the duct is angled at
approximately 45° to both the sagittal and axial
planes.
• It terminates within the sublingual papilla in the
anterior floor of the mouth.
• As the duct courses upward, the lingual nerve
winds around it, first laterally, then inferiorly, and
finally medially
Submandibular Gland
46.
47. Submandibular gland
• Serous acini (90%), with a mucinous acinar component (10%).
• Adipose tissue is not a significant component of the glandular
parenchyma, as it is in the parotid.
• Arterial supply- branches of external maxillary and lingual arteries.
• Sympathetic innervation - carotid plexus,
• parasympathetic innervation- facial nerve and possibly the
glossopharyngeal nerves via the chorda tympani nerve and the
submandibular ganglion.
• Glandular lymphatic drainage - submandibular nodes (level I).
48.
49. Sublingual Gland
• The sublingual gland is the smallest of the major
salivary glands,
• about half the size of the submandibular gland,
• weighing only about 2 g, measuring about 2.5 cm
• shaped like a flattened almond
50. Sublingual Gland
• Lies submucosally against the sublingual
depression of the lingual mandibular surface,
– adjacent to the symphysis,
– on the mylohyoid muscle.
• The lingual nerve and Wharton’s duct separate the
medial sublingual gland contour from the
genioglossus muscle.
• no well-defined capsule
• composed entirely of mucinous acini.
51. Sublingual Gland
• There are about 20 individual small ducts (the ducts of
Rivinus), most of which open independently into the
floor of the mouth along the sublingual papilla and fold.
• Occasionally some of these ducts fuse to form
Bartholin’s duct, which in turn opens into Wharton’s
duct.
• The sublingual innervation is identical to that of the
submandibular gland.
• The gland’s lymph drains into the submental and
submandibular lymph nodes (level I).
52. Minor Salivary Glands
• within the submucosa of the oral cavity, palate,
paranasal sinuses, pharynx, larynx, trachea, and
bronchi.
• concentrated in the buccal, labial, palatal, and
lingual regions.
• The gingivae, anterior hard palate, and true vocal
cords have relatively sparse concentrations of
MSG.
53. Minor Salivary Glands
• MSG acini are either entirely mucinous (e.g., hard palate) or mixed
seromucous glands (e.g. sinonasal, oral).
• The acinar clusters lead to intercalated ducts, striated ducts, and excretory
ducts that terminate as mucosal pores.
• The autonomic secretory function of the upper aerodigestive tract MSG is
controlled by the following ganglia:
– Sphenopalatine (pterygopalatine) ganglia, located near the sphenopalatine
foramina of the medial pterygopalatine fossae, innervate the paranasal sinuses,
nasal cavity, portions of the palate, and the uppermost pharynx;
– Otic ganglia, located along the medial aspect of the mandibular nerves below the
skull base, innervate the buccal mucosa;
– Submandibular ganglia, innervate the floor of the mouth and the anterior
tongue; and finally, the pharyngeal plexus innervates the pharynx
54. MICROSTRUCTURE
• The structure of the salivary glands is similar to other
exocrine glands, comprising a series of secretory units
(acinar cells) clustered around a central lumen.
• These acini comprise the terminal or secretory end-piece of
the gland, situated farthest from the oral cavity.
• They are supported by the myoepithelial cells and a
basement membrane.
• From each acinus the secretions pass to a series of
interconnected ducts before passing out through the major
salivary duct into the oral cavity.
55. MICROSTRUCTURE
• Each acinus comprises a series of polygonal
cells on a basement membrane around a
central ductal lumen.
• The acinar cells are classified histologically
into two types – serous cells and mucous cells
according to their appearance after staining
with eosin and heamatoxylin (histochemical
term rather than a functional).
57. Serous Cells
• Stain blue; make up most of the acini of the parotid gland
and of von ebner.
• Large, polygonal.
• Nucleus lying towards the basement membrane.
• Contain extensive endoplasmic reticulum and
mitochondria,
• In the luminal portion of the cells are granules and vacuoles
which fill up during resting periods but discharge by
exocytosis on stimulation, some of these contain amylase.
• secretion more serous than other glands
58. Mucous cells
• Predominantly pink – staining cells.
• Staining properties resemble those of other cells elsewhere
which produce mucoid substances,
• Since the secretions of these cells are viscous and rich in
protein – carbohydrate complex, they have been referred
to as mucous cells.
• The acinar cells of the submandibular and sublingual glands
are said to comprise mucous cells. The general form and
appearance of mucous cells is not dissimilar to that of
serous cells.
• Mucous cells show more areas of smooth parallel cisternae
and have larger secretory vacuoles.
59. DUCTS
Intercalated duct cells
• The secretions pass from the acinus to a short
intercalated duct: the duct cells tend to be
cuboidal, they have large central nucleus and
many mitochondria and little endoplasmic
reticulum.
• The duct lining cells are closely interdigitated.
• Contain zymogen granules, which may contribute
to stable changes in salivary composition.
60.
61. DUCTS
Striated duct cells
• The intercalated duct then pass abruptly into another short but wide,
striated duct, the striated duct are lined by cells which are much more
columnar than the cells of the intercalated duct.
• The cells have marked cellular membrane interdigitations projecting
towards the lumen.
• Striated ducts actively resorb sodium ions from the primary acinar
secretion, with the associated capillaries then transporting the ions away
from the glands into systemic circulation.
• These striated ducts then pass abruptly into two epithelial cell layered
excretory ducts and finally to the stratified squamous epithelial cell lined
terminal duct.
• Although these latter excretory ducts resorb electrolytes from the primary
secretion, they are probably less efficient than the stratified duct lining cells.
62. Myoepithelial cells
• Constrict the acini and ducts to facilitate
salivary flow.
• Nucleus lies in a broader part of the cell and is
surrounded by mitochondria and strands of
endoplasmic reticulum.
• Remainder of the cells contain- myofibrils.
63. SALIVA
• Three major glands and about 400 minor glands located within the
oral cavity produce saliva.
• A healthy adult : 500–1,500 mL saliva/day at a rate of approximately
0.5 mL/min.
• Multitude of functions: maintaining homeostasis; promoting
wound healing; lubricating the oral cavity; facilitating mineralization
of dental surfaces; digesting carbohydrates by salivary α-amylase;
digesting lipids via salivary lipase; and facilitating chewing,
speaking, swallowing, and taste perception.
• Help maintain oral hygiene by clearing and inhibiting growth of
microorganisms.
64.
65. MECHANISM OF SALIVARY SECRETION
• Stimulation of secretomotor nerves- release
of neurotransmitters- act on membrane
receptor sites on the acinar cells to
stimulate secretion.
Formation of the acinar fluid
• The acinar fluid consists of water, ions, small
molecules, synthesized by the cells.
• This fluid arises from the interstitial fluid, which in turn
arises from the blood in the capillaries.
66. MECHANISM OF SALIVARY SECRETION
• The acinar cells behave as if freely permeable to
lipid-soluble substances and water, but much less
permeable to other molecules.
– Entry of glucose and amino–acids probably occurs by
active transport, their concentration in acinar fluid is
low.
• The ions of the acinar fluid are broadly similar to
those of interstitial fluid.
• Sodium and chloride concentration are similar to
those of plasma
67. MECHANISM OF SALIVARY SECRETION
• Active transport of these two ions at the luminal
membrane is the major factor producing an osmotic
force to speed water movement through the acinar
cells.
• Potassium is lost from the acinar cells to the acinar
fluid on stimulation and high acinar potassium level
may arise from a cell membrane permeability when
exposed to acetylecoline.
• Synthesis of salivary proteins occurs at the
ribosomes and the proteins pass into the cisternae
of the endoplasmic reticulum ; to be secreted from
the cell surface by exocytosis.
68. MODIFICATIONS OF THE ACINAR
FLUID
Modification in the intercalated duct :
• Involved in the initial secretion; though
histologically they do not resemble secretory
cells.
• It is possible that the loss of potassium from
the gland which occurs on stimulation may
take place here as well as in the acinar cells.
69. MODIFICATIONS OF THE ACINAR
FLUID
Modification in the striated duct :
• transformed from an isotonic, or slightly,
hypertonic fluid, with ionic concentration
similar to plasma, to a hypotonic fluid, with
low sodium and chloride concentration.
70. MODIFICATIONS OF THE ACINAR
FLUID
• Sodium is actively transported across the cell -
concentration gradiant increases- luminal fluid,
resulting in diffusion of sodium into the cells from
the lumen.
• The active transport of sodium is linked with
active transport of potassium in the opposite
direction and also with passive diffusion of
chloride to maintain the electrochemical balance.
71. MODIFICATIONS OF THE ACINAR
FLUID
• Bicarbonate is actively secreted to the lumen in this
part of the gland. The cells behave as if largely
impermeable to water, so that although salts are
conserved in the area, water is not resorbed and a
hypotonic secretion results.
• Stimulation either of sympathetic or parasympathetic
nerves causes activation of the duct cells.
• Resting transmembrane potential of cells of the
striated ducts is around – 80 mv On stimulation of the
glands, the transmembrane potential on the luminal
side of the cells becomes much less negative (around –
20 mv).
72. Modification in the distal excretory
ducts
• In the distal part of the excretory ducts
partial re-equilibration of saliva with plasma
occurs and concentration of ions return from
extreme values to more plasma like
concentrations.
73. CONTROL OF SECRETION
• Controlled by a salivary center composed of nuclei in the medulla but
there are specific triggers for this secretion.
Afferent pathways (stimuli)
Local factors
• The act of chewing, the sensation of taste, the irritation of the
mucous membrane - reflexly produce salivation.
• The fibers carrying sensations of taste and touch are carried in the
same nerves carrying the secretomotor fibers – i.e., the chorda
tympani fibers in the lingual nerve (which originate in the facial nerve)
from the anterior 2/3rd of the tounge and glossophargneal nerve from
the poterior 1/3 of tounge.
• The sensation of smell and sight from the nose and eyes are carried by
the 1st and 2nd cranial nerves respectively.
74. Psychic stimuli
• The sight of food, talking about or the noise of food
preparation are sufficient to activate the conditioned
reflexes (influenced by higher centers,
ex: hypothalamus.)
Stimulation from other organs
• Esophageal irritation causes reflex salivation, although
gastric irritation leads to increased salivation as a
component of the nausea / vomiting reflex.
75. Central control
• The afferent stimuli reach the brain and spinal cord and are finally
integrated in the cell bodies of the preganglionic secretomotor
neurons- Where efferent secretomotor impulses are generated.
• Cell bodies of parasympathetic neurons- in the nuclei of facial
and glossophsyngeal nerves.
• The area which gives salivary response on stimulation is termed
‘nucleus salivatorius’. The nucleus salivatorius has been divided
into two components.
– Superior salivary nucleus : stimulations of which causes secretion of
submandibular and sublingual glands.
– Inferior salivary nucleus : stimulation causes secretion of parotid glands.
76. • cell bodies of the sympathetic nervous system
- in the lateral columns of the first five
thoracic nerves.
• The secretomotor cell-bodies, in addition
receive inputs, both excitatory and inhibitory,
from other parts of the brain.
• Hypothalamic activity is also associated with
salivary responses.
77. THE EFFERENT PATHWAY
• The flow of saliva is controlled entirely by
nervous stimuli.
• Control exerted mainly by parasympathetic, but
also by sympathetic stimuli.
• Parasympathetic fibers to the submandibular and
sublingual glands arise from the superior salivary
nucleus in the medulla as nervous intermedins -
geniculate ganglion - descend through the facial
N.- chorda tympani- lingual N. - submandibualar
ganglion- secretory and dialatory fibers to glands.
78. THE EFFERENT PATHWAY
• The parasympathetic fibers to the parotid gland arise from
the inferior salivatory nucleus (dorsal nucleus of the IX
nerve) in the medulla- descend through glossophargneal N.
- tympanic branch -tympanic plexus -lesser superior
petrosal nerve -otic ganglion- post ganglionic fibers- parotid
gland through the auriculotemporal nerve to supply it with
secretory and dilator fibers.
• The sympathetic fibers to all these glands synapse in the
superior cervical ganglion- postganglionic fibers- pass along
the walls of the arteries and supply all the salivary glands.
• The sympathetic fibers end in the serous gland or the
serous part of the mixed gland and supply vasoconstrictor
fibers to the vessels of the glands and myoepitheilial cells
of the ducts.
79. Diagnostic Uses of Saliva
• Human saliva harbors proteins, lipids, RNA,
DNA, and some 700 microbial species.
• A biofluid for early disease detection and
prognosis, risk stratification, and monitoring
treatment response.
• Used for diagnosis and prognosis of oral,
head, and neck cancers, periodontal diseases,
diabetes, and autoimmune disorders.
80. Other diagnostic uses
• Biomarkers identified in saliva for detecting early-stage
pancreatic cancer.
– UCLA Newsroom. Researchers find biomarkers in saliva for detection of early-stage pancreatic cancer. Available at the UCLA
Newsroon online. (Accessed August 2012).
• Soluble c-erbB-2Her2/neu levels in saliva may be useful in
detecting and monitoring recurrence of breast cancer.
– Streckfus CF, Mayorga-Wark O, Arreola D, et al. Breast cancer related proteins are present in saliva and are modulated
secondary to ductal carcinoma in situ of the breast. Cancer Invest 2008;26:159–67.
• Salivaomics is an open-access database that contains
salivaomics-based studies and includes information on
the biology, diagnostic potential, pharmacogenomics,
and pharmacoproteomics of saliva.
81. Saliva Proteome
• Human saliva is a plasma ultra filtrate and contains
proteins either synthesized in situ in the salivary glands
or derived from blood.
• It contains biomarkers derived from serum, gingival
crevicular fluid, and mucosal transudate.
• To date, researchers have identified 2,340 proteins in
the salivary proteome, of which 20–30% are also found
in blood,
– an encouraging indicator for the clinical utility of saliva as a
diagnostic fluid.
• Bandhakavi S, Stone MD, Onsongo G, et al. A dynamic range compression and three-dimensional peptide
fractionation analysis platform expands proteome coverage and the diagnostic potential of whole saliva. J
Proteome Res 2009;8:5590–600.
82. Saliva Proteome
• In contrast to the plasma proteome, in which 99% of the total
protein content is contributed by 22 highly abundant proteins,
the 20 most abundant proteins in human whole saliva (WS)
constitute only 40% of the protein content.
• This composition suggests that detecting biomolecules of clinical
sensitivity and specificity in saliva should be feasible and easier
than in blood.
• Unlike the plasma proteome, however, the WS proteome is highly
susceptible to a variety of physiological and biochemical
processes, such as salivary protein modifications occurring in the
mouth that are catalyzed by host and bacterial derived enzymes.
Such modifications also could present unique challenges for
clinical saliva proteomics.
83. • The dynamic range of proteins in saliva is
another challenge.
• α-amylase- present at mg/mL conc.
• IL-6 and IL-8 only pg/mL.
• This disparity highlights the importance of
developing tools and strategies for detecting
low abundance proteins having clinical
relevance in saliva.
Saliva Proteome
84. • How molecules are transported from blood into
saliva- important for successful use of saliva as a
diagnostic fluid.
• Lipophilic molecules such as steroid hormones
passively diffuse into saliva, while water and
electrolytes pass through the pores of acinar cells.
• Various peptides in blood move through protein
channels, and large proteins are transported via
pinocytosis .
Saliva Proteome
Yang Foo JY, Wan Y, Kostner K, et al. NT-ProBNP levels in saliva and its clinical
relevance to heart failure. [Epub] PLoS One October 31, 2012
85. Commercially Available Saliva Tests
• Two U.S. companies were early pioneers of oral diagnostics:
Epitope, Inc. and Saliva Diagnostic Systems, Inc.
– They both commercialized saliva collection devices in the early 1990s,
– In 1996 FDA approved Epitope’s Orasure HIV test, the first test that
used oral fluid to test for an infectious disease.
• Recently FDA (2012) has approved first over-the-counter salivary
HIV test that allows people to test themselves in the privacy of their
homes for the HIV virus.
– The OraQuick HIV test, which takes only 15 minutes from start to
finish, detects the presence of HIV antibodies in saliva via mouth
swab.
86. Commercially Available Saliva Tests
• Several companies have commercial tests to detect drugs-of-abuse in
a spit sample, including Cozart Biosciences, Securetec, and Mavand.
• Some of these companies send their kits via regular mail to
customers, allowing individuals to collect their own saliva either in a
cup or with a swab and send the sample to lab for analysis.
• Other tests target DNA in saliva. Canada-based DNA Genotek was
the first company to commercialize a broad range of saliva collection
tools for genotyping based on PCR, microarrays, and sequencing.
– My PerioPath is a DNA test that determines the risk of periodontal
infections by detecting bacterial pathogens in saliva.
– OraRisk HPV is a salivary test that determines an individual’s risk of
developing HPV-related oral cancers.
• It identifies various HPV genotypes, including HPV 8, 11, 16, and 18.
87. Emerging Clinical Applications
• Other applications of salivary diagnostics are emerging, including
for the detection of
• cardiovascular disease
– Yang Foo JY, Wan Y, Kostner K, et al. NT-ProBNP levels in saliva and its clinical relevance to heart failure. [Epub] PLoS One
October 31, 2012.
• and head and neck cancer
– Ovchinnikov DA, Cooper MA, Pandit P, et al. Tumour-suppressor gene promoter hypermethylation in saliva of head and neck
cancer patients. Transl Oncol 2012;5:321–6.
• Salivary C-reactive protein (CRP) levels can be used as a biomarker
to differentiate patients with ischemic heart disease from healthy
controls .
• Salivary endothelin conc and natriuretic peptide- to assess heart
failure.
88. Roadblocks to Advancement
• Analytes in saliva are usually present at only
0.1–0.001 of the levels found in blood;
– Therefore, very sensitive detection technology is
required.
• Lack of information about reference ranges of
molecules in saliva within a healthy control
population.
89. • To be clinically useful, there must be reliable
correlations between levels of the target
substance in saliva and in blood or plasma.
– Ex: salivary diagnostics are not well suited to
measure glucose levels because blood and salivary
levels of glucose are poorly correlated.
Roadblocks to Advancement
90. • Contamination of saliva with blood – false
positive result.
– Bleeding after brushing or flossing occurs frequently/
high false-positive rates.
• Research also is needed on how levels of
molecules vary diurnally.
– salivary growth hormone levels are higher in the
morning than during the day, which could also be the
case for other biomarkers.
Roadblocks to Advancement
91. • Lack of standardized saliva collection methods
• OraSure saliva collection device detects
hepatitis C virus with greater sensitivity than
the Salivette device .
Roadblocks to Advancement
•Judd A, Parry J, Hickman M, et al. Evaluation of a modified commercial assay in detecting antibody to
hepatitis C virus in oral fluids and dried blood spots. J Med Virol 2003;71:49–55.
92. What Does the Future Hold?
• As our knowledge of the biomolecules present in saliva
grows, the potential applications for oral and systemic
disease diagnosis will expand.
• While the scientific link between salivary biomarkers
and oral diseases is clear,
– more studies are needed to delineate the mechanisms by
which saliva reflects other systemic diseases.
• Furthermore, before saliva can become widely
recognized as a reliable diagnostic fluid,
– need to understand a number of important variables.
93. What Does the Future Hold?
• First, we need to define the normal biological variability of
biomolecules in saliva,
– diurnal rhythms,
– inter- and intra-subject variation,
– Age
– gender effects.
• Influence of diet, medication, smoking, alcohol, and physical activity
status may also influence levels of biomolecules in saliva.
• Variations caused by saliva sampling, handling, and storage conditions
and analytical techniques.
• Since the salivary proteome is sensitive to both extrinsic and intrinsic
factors,
– analyte reference ranges needs to be carefully documented.
94. • Salivary diagnostics has enormous potential for
the future,
– but we need to lay a solid scientific foundation in
the present in order to realize that potential.
• Non-invasive tests for detecting breast cancer,
viral, and bacterial diseases, cardiovascular and
metabolic diseases, and general nutritional
deficiencies could make a tremendous impact
on global health.
95. Commercially available saliva collection devices in use
today: drool collected in a sterile specimen container (A);
Salimetrics oral swab (B).
Saliva collection devices in use
96. Salivette cotton and synthetic device (C); Greiner Bio-
One saliva collection system (D)
